Canon lawyer Jennifer Haselberger had uncovered several computer discs and a white three-ring binder kept in the basement archives of the chancery building — the headquarters of the Archdiocese of St. Paul and Minneapolis. It was evidence from a 2004 internal investigation of sexually explicit images found on the computer of the Rev. Jonathan Shelley, then pastor of St. Jude of the Lake church in Mahtomedi, Minn.

Haselberger, a firebrand top official who joined the archdiocese in 2008, notified Nienstedt....